An intensive effort was directed toward studying the epidemiologic, preventive and therapeutic aspects of the acquired immunodeficiency syndrome. An ongoing study of 1344 health care workers has continued to demonstrate the low risk of human immunodeficiency virus-1 (HIV-1) transmission from patient to health care worker with a seroconversion rate of 0.6% per percutaneous exposure. A 24 month follow-up of 48 high-risk individuals with indeterminate patterns on HIV Western blots failed to reveal a pattern indicative of early exposure and demonstrated a less than 3 month interval between polymerase chain reaction (PCR) positively and full seroconversion. Immunization of healthy human volunteers to the gpl6O envelope precursor protein of HIV-1 was capable of inducing group specific T lymphocytes directed toward the HIV-1 envelope and titers of neutralizing antibodies as high as 1:800. A placebo controlled trial of interferon-alpha in patients with early HIV-1 infection demonstrated a decrease in the rate of progression for patients on interferon. Phase I trials of 3'-azido-2',3'-dideoxyuridine and rCD4-IqG failed to demonstrate efficacy in HIV infection as manifest by lack of significant change in surrogate markers. GM-CSF was found capable of reversing the neutropenia caused by the combination of interferon-alpha and ZDV. A clinical trial was initiated to compare the effects of ZDV to interferon-alpha to a combination of the two drugs in patients with early HIV-1 infection. A masked, randomized, delayed therapy controlled trial of foscarnet demonstrated this drug to be of benefit to patients with AIDS related CMV retinitis. Phase I/II trials were initiated of ZDV+IL-2, interferon-alpha+IL-2, DDI+interferon-alpha and BW566C80, the latter for the treatment of pneumocystis carinii pneumonia and toxoplasmosis. Immunotherapy protocols were initiated involving active immunization of HIV-1 infected individuals with HIV-1 gpl60 or p24 and passive immunotherapy utilizing peripheral blood lymphocytes and bone marrow from gpl6O primed donors.